Johannes T.B. Overvelde

• Doctor of Philosophy
• Associate Professor at AMOLF & Eindhoven University of Technology

Metamaterials are artificial materials that derive their unusual properties from their periodic architecture. Some metamaterials can deform their internal structure to switch between different properties. However, the precise control of these deformations remains a challenge, as these structures often exhibit non-linear mechanical behavior. We intr...

Significance In the last century, robots have been revolutionizing our lives, augmenting human actions with greater precision and repeatability. Unfortunately, most robotic systems can only operate in controlled environments. While increasing the complexity of the centralized controller is an instinctive direction to enable robots that are capable...

Despite exciting developments in soft robotics, fully autonomous systems remain elusive. Fluidic circuits could enable fully embedded control of soft robots without using electronics. In this work, we introduce a simple and compact soft valve with intentional hysteresis, analogous to an electronic relaxation oscillator. By integrating the valve wit...

Many patients with end-stage heart disease die because of the scarcity of donor hearts. A total artificial heart (TAH), an implantable machine that replaces the heart, has so far been successfully used in over 1,700 patients as a temporary life-saving technology for bridging to heart transplantation. However, after more than six decades of research...

Rather than depending on material composition to primarily dictate performance metrics, metamaterials can leverage geometry to achieve specific properties of interest. For example, reconfigurable metamaterials have enabled programmable shape transformations, tunable mechanical properties, and energy absorption. While several methods exist to fabric...

Soft robotic actuation concepts meet and sometimes exceed their natural counterparts. In contrast, artificially recreating natural levels of autonomy is still an unmet challenge. Here, we come to this conclusion after defining a measure of energy- and control-autonomy and classifying a representative selection of soft robots. We argue that, in orde...

Motivated by the need to harness the properties of renewable and biodegradable polymers for the design and manufacturing of multi-scale structures with complex geometries, we have employed our additive manufacturing platform that leverages molecular self-assembly for the production of metre-scale structures characterized by complex geometries and h...

In robotics, achieving adaptivity in complex environments is challenging. Traditional robotic systems use stiff materials and computationally expensive centralized controllers, while nature often favors soft materials and embodied intelligence. Inspired by nature's distributed intelligence, this study explores a decentralized approach for robust be...

Phononic crystals are renowned for their distinctive wave propagation characteristics, notably bandgaps that offer precise control over vibration phenomena, positioning them as a critical material in advanced vibro-elastic engineering and design. We investigate how pore shapes influence the bandgap in continuum two-dimensional phononic crystals mad...

Fluidic circuits are a promising recent development in embodied control of soft robots. These circuits typically make use of highly non-linear soft components to enable complex behaviors given simple inputs, such as constant flow or pressure. This approach greatly simplifies control, as it removes the need for external hardware or software. However...

Soft robots are intrinsically capable of adapting to different environments by changing their shape in response to interaction forces. However, sensory feedback is still required for higher level decisions. Most sensing technologies integrate separate sensing elements in soft actuators, which presents a considerable challenge for both the fabricati...

Elastomeric elastocaloric regenerators have great potential for use in low-stress elastocaloric cooling devices. However, these regenerators display an asymmetric fluid exchange when operating in an active elastocaloric cooling cycle, due to the large required strains and associated volume change. During strain, the fluid volume increases, which pa...

Soft robots are intrinsically capable of adapting to different environments by changing their shape in response to interaction forces with the environment. However, sensing and feedback are still required for higher level decisions and autonomy. Most sensing technologies developed for soft robots involve the integration of separate sensing elements...

Sub‐millimeter robots—microrobots—that can autonomously perform mechanical work at the microscale would radically change new areas of human activity such as micromanipulation, microfabrication, or healthcare. Sets of identical microrobots that can connect into different, larger structures open the possibility for a “universal” microrobotic unit tha...

Biological movement is a source of inspiration for designing soft robots that use fluidic actuation for adaptive gripping and locomotion. While many biological systems use networks of non‐Newtonian fluid for movement, to date, most soft robots use Newtonian fluids or pneumatics. Herein, yield stress fluids to manufacture and operate soft devices ar...

The folding behavior of origami-inspired metamaterials is often described by linear rotational springs and rigid faces. However, other folding modes and multistatbility appears when assuming elastic faces, specially when assuming (non-euclidean) crease patterns in 2D or 3D where a high number of hinges meet at their vertices. Instead, here we study...

An interplay between deswelling and buckling in a polymer gel is harnessed to achieve sequential snap events for repeatable jumping motion, opening the door to autonomously moving soft robots.

Scatterometry is an optical metrology technique, in which light scattered from a specifically designed grating stack (overlay target) is measured in the far-field. Using 1D periodic overlay target designs the technique has been shown to have nanometer-scale sensitivity to spatial misalignments of subsequent patterned layers, which are also known as...

Metamaterials are man‐made materials which get their properties from their structure rather than their chemical composition. Their mesostructure is specifically designed to create functionalities not found in nature. However, despite the broad variety of metamaterials developed in recent years, a straightforward procedure to design these complex ma...

A multi-nozzle system has been devised that allows the 3D printing of objects using several viscous materials, thereby allowing control over the material properties of objects at the submillimetre scale. A multinozzle system for the 3D printing of voxellated objects. MM3D printheads

Soft robots powered by pressurized fluid have recently enabled a variety of innovative applications in areas as diverse as space exploration, search and rescue systems, biomimetics, medical surgery, and rehabilitation. Although soft robots have been demonstrated to be capable of performing a number of different tasks, they typically require indepen...

In viscoelastic materials, individually short-lived bonds collectively result in a mechanical resistance which is long-lived but finite, as ultimately cracks appear. Here we provide a microscopic mechanism by which cracks emerge from the nonlinear local bond dynamics. This mechanism is different from crack initiation in solids, which is governed by...

The first book on active matter, an emerging field focused on programming physical materials to assemble themselves, transform autonomously, and react to information. The past few decades brought a revolution in computer software and hardware; today we are on the cusp of a materials revolution. If yesterday we programmed computers and other machine...

Using foldable origami-like structures, we design reconfigurable and switchable acoustic waveguides composed of interconnected periodic arrays of hollow tubes to manipulate and guide sound. We demonstrate both numerically and experimentally that upon application of external deformation, the structure is folded and transformed to one-, two-, and thr...

Advances in fabrication technologies are enabling the production of architected materials with unprecedented properties. Most such materials are characterized by a fixed geometry, but in the design of some materials it is possible to incorporate internal mechanisms capable of reconfiguring their spatial architecture, and in this way to enable tunab...

Soft bending actuators are inherently compliant, compact, and lightweight. They are preferable candidates over rigid actuators for robotic applications ranging from physical human interaction to delicate object manipulation. However, characterizing and predicting their behaviors are challenging due to the material nonlinearities and the complex mot...

We combine numerical simulations and experiments to design a new class of reconfigurable waveguides based on three-dimensional origami-inspired metamaterials. Our strategy builds on the fact that the rigid plates and hinges forming these structures define networks of tubes that can be easily reconfigured. As such, they provide an ideal platform to...

A range of instabilities can occur in soft bodies that undergo large deformation. While most of them arise under compressive forces, it has previously been shown analytically that a tensile instability can occur in an elastic block subjected to equitriaxial tension. Guided by this result, we conducted centimeter-scale experiments on thick elastomer...

The use of soft materials has led to the development of soft devices that have the potential to be more robust, adaptable, and safer for human interaction than traditional rigid systems. State-of-the-art developments push these robotic systems towards applications such as soft rehabilitation and diagnostic devices, exoskeletons for gait assistance,...

Reconfigurable devices, whose shape can be drastically altered, are central to expandable shelters, deployable space structures, reversible encapsulation systems and medical tools and robots. All these applications require structures whose shape can be actively controlled, both for deployment and to conform to the surrounding environment. While mos...

Stiffness of extruded polyhedral. Our work is inspired by snapology, a type of modular unit-based origami in which paper ribbons are folded and assembled to create complex geometric extruded polyhedra. Interestingly, we found that some of the resulting geometries (such as the extruded icosahedron) are stiff and almost rigid, while others (such as t...

Transformable metamaterial. The highly flexible unit cell can be used to form mechanical metamaterials whose shape and volume can be dramatically altered. Here, we connected the outer edges of 64 identical unit cells to form a 4 × 4 × 4 cubic crystal. Importantly, the assembly does not constrain any degrees of freedom, so the mechanical metamateria...

Actuation of the metamaterial. Similar to the unit cell, the shape and volume of the metamaterial can be actively programmed by strategically positioning inflatable pockets on the hinges of the unit cells.

Possible shapes of the unit cell. The unit cell considered in this study can be transformed into multiple highly distinct shapes by varying γ1, γ2 and γ3. Because of contact occurring between its faces, only the combinations of angles contained within the regular tetrahedron with vertices at (γ1, γ2, γ3) = (0, 0, 0), (π, π, 0), (π, 0, π) and (0, π,...

Actuation of the unit cell. The shape and volume of the unit cell can be actively programmed by strategically positioning inflatable pockets on the hinges of the unit cell. By pressurizing the air pockets, the shape of the unit cell can be effectively controlled.

Recovery of the unit cell. The response of the unit cell is always elastic. Even after applying 10,000N no permanent deformation is observed and the fully expanded configuration is recovered after the removal of the applied load.

Supplementary Figures 1-4, Supplementary Table 1 and Supplementary References.

Significance Although instabilities have traditionally been avoided as they often represent mechanical failure, here we embrace them to amplify the response of fluidic soft actuators. Besides presenting a robust strategy to trigger snap-through instabilities at constant volume in soft fluidic actuators, we also show that the energy released at the...

A mechanically tunable macroscale replica of the gyroid photonic crystal found in the Parides sesostris butterfly's wing scales is systematically characterized. By monitoring both photonic frequency changes and the distribution of stress fields within the compressed structure, electromagnetic transmission features are found and can be frequency-tun...

Scripting is a powerful tool that allows you to combine the functionality of the Graphical User Interface (GUI) of Abaqus and the power of the programming language Python. This manual is an introduction to Abaqus script from a practical viewpoint and it tries to explain an easy, fast way to start scripting. If you don’t have experience with the Aba...

Roboticists have begun to design biologically inspired robots with soft or partially soft bodies, which have the potential to be more robust and adaptable, and safer for human interaction, than traditional rigid robots. However, key challenges in the design and manufacture of soft robots include the complex fabrication processes and the interfacing...

Soft fluidic actuators consisting of elastomeric matrices with embedded flexible materials are of particular interest to the robotics community because they are affordable and can be easily customized to a given application. However, the significant potential of such actuators is currently limited as their design has typically been based on intuiti...

Soft sensors comprising a flexible matrix with embedded circuit elements can undergo large deformations while maintaining adequate performance. These devices have attracted considerable interest for their ability to be integrated with the human body and have enabled the design of skin-like health monitoring devices, sensing suits, and soft active o...

We uncover how nonlinearities dramatically influence the buckling of elastic beams by means of experiments, simulations and theory. We show that sufficiently wide, ordinary elastic beams exhibit discontinuous buckling, an unstable form of buckling where the post-buckling stiffness is negative. We develop a 1D model that matches our data and identif...

This Communication presents a class of soft actuated materials that can achieve lifelike motion. By embedding pneumatic actuators in a soft material inspired by biological muscle fibril architecture, and developing a simple finite element simulation of same, we can achieve tunable biomimetic motion with fully soft structures, exemplified here by an...

The cover picture shows the concept and inspiration for a soft actuated material, in this case the muscular structure of the heart. The image depicts the muscular fibers from the heart inspiring the numerical modeling of the actuators and the design of contractile actuators embedded in a soft matrix, as described in the work by C. J. Walsh and co-w...

Adaptive structures allowing dramatic shape changes offer unique opportunities for the design of responsive and reconfigurable devices. Traditional morphing and foldable structures with stiff structural members and mechanical joints remains a challenge in manufacturing at small length scales. Soft structures where the folding mechanisms are induced...

By introducing a periodic array of pores in an elastic matrix, instabilities with wavelengths that are of the order of the size of the microstructure can be triggered. Interestingly, these instabilities can be utilized to design a novel class of responsive materials. Possible applications include materials with unusual properties such as negative P...

We exploited mechanical instability in shape memory polymer (SMP) membranes consisting of a hexagonal array of micron-sized circular holes and demonstrated dramatic color switching as a result of pattern transformation. When hot-pressed, the circular holes were deformed to an array of elliptical slits (with width of tens of nanometers), and further...

Soft cellular structures that comprise a solid matrix with a square array of holes open avenues for the design of novel soft and foldable structures. Our results demonstrate that by simply changing the shape of the holes the response of porous structure can be easily tuned and soft structures with optimal compaction can be designed.

In this thesis the possibility of a flow-inspired Meshless Method based topology optimization method is explored. More specific, an investigation is carried out to the possibility of using the position of the nodes from the meshless EFG method as design variables in topology optimization. In order to determine the possibility of using the nodal pos...